Patent application title: Full-wave di-patch antenna

Abstract:

A full-wave di-patch antenna having two half-wave patch antennas located
such that the feed points are facing one another and are brought out to a
balanced transmission line having two conductors of microstrip feed
lines. The phase of the current and the voltage is inverted 180 degrees
between the two patches relative to the mechanical structure. The
physical spacing of the two patches from center-to-center is one guide
wavelength long. The two patches are disposed on a dielectric substrate
which is in turn disposed over a ground plane. The two patches can take
any of a number of shapes including a rectangle.

Claims:

1. A full-wave di-patch antenna comprising:a common differential feed
point having a positive terminal and a negative terminal;a differential
feed line pair comprising a first feed line having a distal end coupled
to the positive terminal and a second feed line having a distal end
coupled to the negative terminal, wherein the first and second feed lines
are adjacent to one another at the distal end;a first patch antenna
connected to a proximal end of the first feed line;a second patch antenna
connected to a proximal end of the second feed line, the first patch
antenna and the second patch antenna are spaced a full guide wavelength
apart, wherein the first and second patch antennas are configured to
maximize energy transfer efficiency therebetween to operate as a single
full-wave structure.

2. The antenna of claim 1, further comprising a dielectric substrate upon
which the patch antennas are disposed.

3. The antenna of claim 1, wherein current and voltage delivered to the
feed points of the first and second patch antennas are 180 degrees out of
phase with respect to one another individually and in phase with one
another with respect to the antennas.

4. The antenna of claim 1, wherein the first and second feed lines are
parallel with one another at the distal end.

5. The antenna of claim 1, wherein the first and second feed lines each
have a first width dimension near the proximal end and a second width
dimension near the distal end, wherein the second width dimension of each
feed line is larger than the first width dimension.

6. The antenna of claim 1, wherein the first and second patch antennas are
the full guide wavelength apart between centers of the first and second
patch antennas.

7. The antenna of claim 1, wherein the first and second patches each have
a shape of a rectangle.

8. The antenna of claim 1, wherein the first and second patch antennas are
rectangular in shape, wherein a length dimension of each patch antenna is
one-half a guide wavelength.

9. A full-wave di-patch antenna comprising:a first patch antenna having a
center feed inset along an edge, wherein the first patch antenna is
rotated about ninety degrees in relation to a common feed point; anda
second patch antenna having a center feed inset along an edge, the second
patch antenna is rotated about ninety degrees in relation to the common
feed point, wherein the center inset feeds to first patch antenna and the
second patch antenna are rotationally oriented 180 degrees from one
another.

10. The antenna of claim 9, further comprising a dielectric substrate upon
which the patch antennas are disposed.

11. The antenna of claim 9, wherein current and voltage delivered to the
feed points of the first and second patch antennas are 180 degrees out of
phase with respect to one another individually and 180 degrees in phase
with one another with respect to the antennas.

12. The antenna of claim 9, wherein the first and second patch antennas
are the full guide wavelength apart between centers of the first and
second patch antennas.

13. The antenna of claim 9, wherein the first and second patches each have
a shape of a rectangle.

14. The antenna of claim 9, wherein the first and second patch antennas
are rectangular in shape, wherein a length dimension of each patch
antenna is one-half a guide wavelength.

15. The antenna of claim 9, wherein the first and second feed lines are
parallel with one another at the distal end.

16. The antenna of claim 9, wherein the first and second feed lines each
have a first width dimension near the proximal end and a second width
dimension near the distal end, wherein the second width dimension of each
feed line is larger than the first width dimension.

17. A full-wave di-patch antenna comprising:a common differential feed
point having a positive terminal and a negative terminal;a differential
feed line pair comprising a first feed line having a distal end coupled
to the positive terminal and a second feed line having a distal end
coupled to the negative terminal, wherein the first and second feed lines
are adjacent to one another at the distal end;a first patch antenna
having a first feed inset connected to a proximal end of the first feed
line at a center of an edge, wherein the first feed inset is oriented
approximately 90 degrees with respect to the distal end of the first feed
line; anda second patch antenna having a second feed inset connected to a
proximal end of the second feed line at a center of an edge, wherein the
second feed inset is oriented approximately 90 degrees with respect to
the distal end of the second feed line and 180 degrees with the first
feed inset.

18. The antenna of claim 17, further comprising a dielectric substrate
upon which the patch antennas are disposed.

19. The antenna of claim 17, wherein current and voltage delivered to the
feed points of the first and second patch antennas are 180 degrees out of
phase with respect to one another individually and 180 degrees in phase
with one another with respect to the antennas.

20. The antenna of claim 17, wherein the first and second patch antennas
are the full guide wavelength apart between centers of the first and
second patch antennas.

21. The antenna of claim 17, wherein the first and second patches each
have a shape of a rectangle.

22. The antenna of claim 17, wherein the first and second patch antennas
are rectangular in shape, wherein a length dimension of each patch
antenna is one-half a guide wavelength.

23. The antenna of claim 17, wherein the first and second feed lines are
parallel with one another at the distal end.

24. The antenna of claim 17, wherein the first and second feed lines each
have a first width dimension near the proximal end and a second width
dimension near the distal end, wherein the second width dimension of each
feed line is larger than the first width dimension.

Description:

[0002]Over the years, many antenna forms have been developed and employed.
As the signal wavelengths have gotten shorter and shorter, new antennas
have been needed and developed. One example prior art antenna is
demonstrated in FIG. 1 which shows a schematic diagram of a canonical
half-wave microstrip patch antenna 10 with inset feed 12. Unfortunately,
this is an unbalanced antenna form which may not be suitable for all
applications.

OVERVIEW

[0003]A full-wave di-patch antenna having two half-wave patch antennas
located such that the feed points are facing one another and are brought
out to a balanced transmission line consisting of two conductors of
microstrip feed lines is disclosed. The phase of the current and the
voltage is inverted 180 degrees at the feedpoints between the two patch
antennas relative to the mechanical structure. The physical spacing
between the two patch antennas is about one guide wavelength in length
from their respective centers. In an embodiment, the two patches are
disposed on a dielectric substrate which is in turn disposed over a
ground plane. The two patches can take any of a number of shapes
including a rectangle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004]The accompanying drawings, which are incorporated into and
constitute a part of this specification, illustrate one or more exemplary
embodiments of the present invention and, together with the detailed
description, serve to explain the principles and exemplary
implementations of the invention.

[0007]FIG. 2 illustrates a schematic wiring diagram of a full-wave
di-patch antenna according to an embodiment;

[0008]FIG. 3 illustrates a diagram of a full-wave di-patch antenna
attached to a dielectric substrate and a ground plane according to an
embodiment;

[0009]FIG. 4 illustrates a cross section view of the schematic of FIG. 3
according to the an embodiment;

[0010]FIG. 5 illustrates a block diagram of a system incorporating the
full-wave di-patch antenna according to an embodiment; and

[0011]FIG. 6 illustrates a diagram of a full-wave di-patch antenna
attached to a dielectric substrate and a ground plane according to an
embodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS

[0012]Various example embodiments of the present invention are described
herein in the context of a full-wave di-patch antenna. Those of ordinary
skill in the art will realize that the following detailed description of
the present invention is illustrative only and is not intended to be in
any way limiting. Other embodiments of the present invention will readily
suggest themselves to such skilled persons having the benefit of this
disclosure. Reference will now be made in detail to exemplary
implementations of the present invention as illustrated in the
accompanying drawings. The same reference indicators will be used
throughout the drawings and the following detailed descriptions to refer
to the same or like parts.

[0013]In the interest of clarity, not all of the routine features of the
exemplary implementations described herein are shown and described. It
will of course, be appreciated that in the development of any such actual
implementation, numerous implementation-specific decisions must be made
in order to achieve the specific goals of the developer, such as
compliance with application- and business-related constraints, and that
these specific goals will vary from one implementation to another and
from one developer to another. Moreover, it will be appreciated that such
a development effort might be complex and time-consuming, but would
nevertheless be a routine undertaking of engineering for those of
ordinary skill in the art having the benefit of this disclosure.

[0014]FIG. 2 illustrates a schematic diagram of a full-wave di-patch
antenna according to an embodiment. In an embodiment, the di-patch
antenna 20 shown includes a first patch antenna 22 and a second patch
antenna 24. The first and second patch antennas 22, 24 are each coupled
to respective feed lines 26, 28. The patch antennas 22, 24 are shown to
have a rectangular shape with dimensions (L×W), although the
antennas 22, 24 may have any other appropriate shape.

[0015]In the case of the rectangular patch shape, the length (L) dimension
of the antenna is a critical dimension in which the length dimension L is
one-half of the guide wavelength, λg in an embodiment. The
guide wavelength λg is a half wave length when taking into
consideration the dielectric properties of the substrate 32 upon which
the patch antenna 20 is disposed (FIG. 3) as well as other
electromagnetic modes that may occur within the dielectric substrate. The
λg is affected by the relative permittivity (.di-elect
cons.r) and the thickness of the substrate, and the size of the
substrate and groundplane relative to λ. It is analytically
difficult to predict the exact value of L for a particular structure, but
very good results are achieved by use of electromagnetic modeling
programs. The width (W) dimension is less critical than the length
dimension and can be a fraction or multiple of the L dimension. In an
embodiment, the patch antennas 22, 24 are square-shaped, whereby the W
dimension is equal to length (λg/2). In an embodiment, as
shown in FIG. 2, the patch antennas 22, 24 have a rectangular shape
wherein the W dimension is one and a half times the length dimension L.
The spacing between the two patch antennas 22, 24, center-to-center as
shown in FIG. 2, is twice the length dimension (2L) of the individual
patch antennas in an embodiment.

[0016]As shown in FIG. 2, two differential or balanced feed lines 26, 28
are coupled to the patch antennas 22, 24. In addition, the first feed
line 26 is also coupled to a positive terminal of a differential feed
point 29 at a distal end, whereas the second feed line 28 is coupled to a
negative terminal of the differential feed point 29 at a distal end. It
should be noted that the positive-negative terminals at 29 may be
reversed in an embodiment. The feed lines 26, 28 are coupled to the inset
feeds 27 at a proximal end, whereby the lines 26, 28 gradually curve at
an angle (26A, 28A). The proximal ends of the feed lines 26, 28 are
connected to the patch antennas at a center point with respect to the W
dimension and are thus rotated ninety degrees relative to the parallel
portions 26B, 28B. In an embodiment shown in FIGS. 2 and 3, following the
angles at 26A, 28A, the feed lines 26, 28 then become parallel with one
another toward their distal ends 26B, 28B. In an embodiment shown in FIG.
6, the feed lines 126, 128 are both parallel and taper outward at a
slight angle. In other words, in the embodiment shown in FIG. 6, the feed
lines are narrow at proximal locations 126A and 128B and widen in width
dimension at the distal locations 126A and 126B. This particular
configuration provides for matching impedance with different feed point
spacing as shown in FIG. 6. It should be noted that other shapes of the
feed lines are contemplated and are not limited to the embodiments only
discussed herein.

[0017]As shown in FIG. 2, the patch antennas 22, 24 face away from one
another and are positioned ninety degrees from and adjacent to the distal
portion of the differential feed lines 26B, 28B. In particular, as shown
in FIG. 2, the patch antenna 22 is positioned -90° with respect to
the distal portion 26B of the differential feed line 26 whereas the patch
antenna 24 is positioned +90° with respect to the distal portion
26B of the differential transmission line 28B.

[0018]In addition, the inset feeds 27 of each antenna 22, 24 are
positioned to face one another and are at a closest distance with respect
to one another. In contrast, the top edges opposite to the inset feed
edges of the antennas 22, 24 are a farthest distance from one another.

[0019]The two differential feed lines 26, 28 form a balanced transmission
line in which the phase of the current and voltage is inverted 180
degrees between the left and right patch antennas 22, 24 in order to
produce in-phase currents and voltages in the left and right patch
elements. In other words, the currents in the transmission lines feeding
the right and left patch antennas 22, 24 are 180 degrees out of phase
with respect to one another, as shown in FIG. 3. However, the currents in
the right and left patch antennas 22, 24 are in phase with one another
collectively when both antennas 22, 24 are viewed with respect to an
external reference. The design incorporates half-wave patch antenna
structures in which there is a half-wave gap or λg/2 between
the edges 30, 32 of the respective patch antennas 22, 24. This results in
a full-wave λg spacing between the centers of the patch
antennas 22, 24 as described above. The radiation pattern phase center is
located at the center point between the patch structures as illustrated.
By use of the antenna structure shown, the need for a matching balun is
eliminated. As a result, maximum energy transfer efficiency is attained.
Further, the full-wave di-patch antenna 20 has higher directive gain than
the half-wave microstrip patch 10 shown in FIG. 1.

[0020]FIG. 3 illustrates a diagram of an assembly of the full-wave
di-patch antenna 20 disposed on a dielectric substrate 30 in accordance
with an embodiment. FIG. 4 is a cross section view, along the line shown
in FIG. 3, of the antenna assembly in FIG. 3. These drawings are not to
scale and are only intended to show a general design of the various
layers. A wide variety of actual implementations may be possible within
the scope of the present invention. Those of ordinary skill in the art
will recognize that the dielectric substrate 30 will likely be much
thinner than shown. The dielectric substrate 30 is made of a low-loss
material such as PTFE based composites, fused silica, ceramic materials,
or the like.

[0021]As shown in FIG. 3, the angled configuration of the first and second
patch antennas 22, 24 allow the currents flowing through both patch
antennas 22, 24 to be in phase with one another, as shown by the arrows.
In particular to FIG. 3, the current in the first patch antenna 22 flows
from left to right, through the feed line 26 to the positive terminal of
the feed point, as shown by the arrows. In addition, as shown in FIG. 3,
the current travels from the negative terminal at the feed point upward
and into the feed line inset in the second patch antenna 24, whereby the
current flowing in the patch antenna 24 also travels left to right, as
shown by the arrows. This configuration thus results in a single
full-wave antenna structure composed of two elements with higher gain
than a single patch antenna shown in FIG. 1 (approximately 9 dBi for the
full-wave antenna compared to 7 dBi of a half wave antenna). In addition,
this configuration provides maximum efficiency of the energy transfer to
the full-wave antenna 22, 24 without requiring the use of a matching
balun.

[0022]The antenna configurations described herein employ one or more full
wave di-patch antennas, whereby the antenna configurations may be used in
several applications. One example application may include millimeter wave
transmitters, receivers, or transceivers using a balanced line feed (FIG.
5). Another example application may be a radar transceiver such as those
used for vehicular collision avoidance (e.g. 77 GHz) as well as radio
frequency identification (RFID), tracking and security systems (e.g. 60
GHz, 92 GHz and/or 120 GHz). Another example may include a passive
millimeter wave detection system such as those that may be employed in
airport security systems, industrial object tracking, through-the-wall
detection systems (24 GHz, 60 GHz, and/or 92 GHz) and the like. A fourth
example may be high speed digital communication systems for data links,
wireless "no cable" links, high-definition video transport, and/or
wireless local area networks using millimeter wave frequencies (60 GHz,
92 GHz, and/or 120 GHz). Those of ordinary skill in the art having the
benefit of this disclosure will realize other applications may exist
which can utilize the antenna configurations described herein. These
configurations are scalable to frequencies up through millimeter and
sub-millimeter ranges, including (but not limited to) the "sub terahertz"
frequencies from 300 GHz through 1 THz.

[0023]In an embodiment, the patch antenna elements and transmission lines
are formed onto a substrate by depositing metal onto the substrate known
as a thin-film process, whereby various methods of thin film metal
deposition may be used. In an embodiment, metal is deposited onto a
substrate via chemical vapor deposition, sputtering or plating. In an
embodiment, gold is deposited over a thin layer of chromium on a fused
silica substrate to form the patch antennas. In an embodiment, the
thickness of the antennas which are built up would be a substrate of 250
micrometers, with a chromium layer of 50 nanometers. This is followed by
a gold layer of 3 micrometers. Other thicknesses and materials may be
used and are dependent upon operating frequency and physical packaging
constraints for a given application.

[0024]Although the antenna configurations are shown and described herein
as having two antennas, it is contemplated that more than two antennas
may be coupled to a pair of differential feed lines in an embodiment. It
is also contemplated that multiple sets of patch antennas may be disposed
on a substrate to increase the amount of gain produced and to provide
phased array beam steering functionality by controlling the phases of the
voltages and currents connected to the feed lines associated with each
set of antenna elements. In one or more embodiments, multiple sets of
antenna structures may be disposed side by side on the substrate. In one
or more embodiments multiple sets of antenna structures are stacked on
top of one another on the substrate to produce greater gain.

[0025]While embodiments and applications have been shown and described, it
would be apparent to those skilled in the art having the benefit of this
disclosure that many more modifications than mentioned above are possible
without departing from the inventive concepts disclosed herein. The
invention, therefore, is not to be restricted except in the spirit of the
appended claims.